NOSEMA-DISEASE. 9 
growth and multiplication of the parasite. The digestive fluids are 
believed to assist in removing the spore coat. The liberated young 
parasite finds its way to the walls of the stomach and invades the 
epithelial cells. Within this epithelial tissue it grows and multiplies 
with great rapidity, giving rise finally to numerous spores. The cells 
of the epithelium at times seem to become virtually filled with the 
parasites (fig. 3; Pis. II and III). That portion of an epithelial 
cell that is normally shed into the lumen of the stomach in case of 
infection bears with it many spores. These are liberated gradually 
from the fragments, become mixed with the partially digested food 
of the stomach, and are carried onward first into the small and then 
into the large intestine and finally pass out of the alimentary tract 
with the excrement. Other bees ingesting these spores become 
infected. This in brief is the life 
cycle * through which the parasite 
passes. 
Nosema apis reaches the tissues of 
the bee by way of the alimentary 
tract. In infecting the stomach the 
parasite reaches the basement mem- 
brane but does not penetrate it (Pis. 
II and III). The muscular part of 
the organ is therefore uninvolved 
(fig. 3). Likewise when the infec- 
tion is found in the Malpighian 
tubules the germ does not proceed , 
j -i i -i Fig. 4. — Spores of Nosema apisas seen in a fresh 
beyond the basement membrane preparation, indicating their general oval form. 
(Pis. II and III). Furthermore the (0^8^-) 
germ does not infect (fig. 1) the pharynx (Phy), the oesophagus ((E), 
the honey sac (MS), the proven triculus (Pvent), the small intestine, or 
the large intestine (Beet) — organs which possess a pronounced chitin- 
ized intima. Infection with the parasite seems, therefore, to be con- 
fined to the epithelium of the stomach and of the Malpighian tubules. 
So far the writer has not encountered the germ in the blood, muscu- 
lature, or any of the other tissues of the body. 
Nosema apis has not been cultivated in pure cultures by artificial 
methods. The nature of the organism makes the accomplishment of 
such a task at the present time especially difficult. Direct proof ob- 
tained by the inoculation of bees with cultures of the parasite has 
not, therefore, been obtained. Fortunately such direct proof is not 
1 Fantham and Porter (1911 and 1912) encountered a parasite in bees taken from colonies affected with 
Isle of Wight disease which they have identified as Nosema apis. Their studies on the morphology of the 
parasite are interesting. 
The morphology of Nosema apis and of Nosema bombycis are apparently quite similar and studies made 
by Stempell (1909) on the latter parasite may be referred to with profit in studying Nosema apis. 
103789— 19— Bull. 780 2 
